This invention relates to purification of phosphoryl chloride. More particularly, the invention relates to the removal of residual phosphorus trichloride from phosphoryl chloride which has been prepared by the oxidation of phosphorus trichloride in air or other oxygen-containing gas.
Phosphoryl chloride is ordinarily prepared by the oxidation of phosphorus trichloride with an oxygen-containing gas (i.e., air or oxygen is bubbled through liquid phosphorus trichloride). During such preparation of phosphoryl chloride, the rate of conversion decreases as less and less phosphorus trichloride is available for reaction due to the dilution of the phosphorus trichloride by the phosphoryl chloride product. Accordingly, conversion of the last, very dilute amounts of phosphorus trichloride is very difficult. Economics dictate that at some predetermined point, the oxidation must be discontinued in view of the time and energy expended. Ordinarily, the conversion is discontinued while a certain amount of phosphorus trichloride remains unconverted. At the present time, phosphoryl chloride, which is prepared by the oxidation of phosphorus trichloride with oxygen, is purified by removal of residual phosphorus trichloride by distillation procedures. Such distillation procedures are, however, time consuming and cannot remove all traces of phosphorus trichloride. Accordingly, it would be of great advantage to be able to purify phosphoryl chloride, which contains residual phosphorus trichloride, without using distillation procedures.